Process of obtaining nitric acid from gas mixtures containing oxids of nitrogen.



'UNITEI.) HTATES PAIENTI ()l liiUlt.

PROCESS OF OBTAINING NITRIC ACID FROM GAS MIXTURES CONTAINING OXIDS OF 7'0 all whom it may concern:

Be it known that l, licnwni titisl-zn, a subjlect of the Grand Duke (it Sain -(lulu!rt! Got-1a, residing at Berlin, (.lcrnmny, have invented certain new and useful llnpl'ounwnts in Processes of Obtaining Concentrated i\'itric Acid from Gas Mixtures (.outninilur Oxids of Nitrogen, of which the following is a, s ecification.

he numerous methods which have been proposed for the oxidation of Rtl]l0S1')ll8l'iC nitrogen by means of electrical discharges, all permit the air to be enriched onl by two to our percent. of nitrous oxid. lhe nitrous oxid content, after its spontaneous transformation into nitrogen dioxid, is brought into contact with water in absorption towers of large dimensions, and thus transformed into nitric zicid. The absorption apparatus is large in size and therefore costl and the process permits the recovery in t e form of 50% nitric acid of only it small portion of the nitric oxid. Far the lar r portion must first be subjected to it cost y concentrating process. The present invention aims to avoid these difficulties in the following manner." The nitric oxids are absorbed in suitable apparatus of comparative] r small s ze by means of a weak basic oxid, characterized the fact that'the nitrates and nitritcs of tiiis base are readily decomposed at high' temperature into its component parts. Care-' lul research has shown t at the oxid otzinc, copper, the rare earths, and possibly the OXldS of magnesium and lend, are extremely well mla ted for this purpose. For example zinc oxii 'combines with nitric oxid ,aecording tothc followingrevcrsible reactions:-

27'no me, Zn (N0,,), Zn son, in the cold this reaction proceeds from lelt to right; but when the mixture of n1-' The absorption of the nitric oxid is acfinn fished my rapidly: and almost abso- Speeiflcation of Letters Patent.

Application filed August 8, 190'?v m'rno sen.

Putonted May 18, 1909.

Serial No. 387,578.

lutcly, and, provided the absorbing material is in the pulverized tor-in and is stirred up, is ucconiplishcd to the point ot' the formation of ncutra' salts. After this stage is reached, the salts obtained nrc beatcd slowly in iron retorts up to 500, during which they giveup the absorbed nitric oxid as pure nitrousm'id This can be made, in proper water drip towers, into-1tJ commercial acid, or can bc coi'idensed as nitrous acid and used as such. The nitric oxid col'nbincs with water according to the reaction.

Another torin of embodiment of this procconsisls in driving oFl the nitric oxid in a \TICUUlIl. decomposition may be obtained at a much lower temperature, thereby effecting a saving in fuel.

What l claim ltS new and desire to securc. by Letters Patent of the United Statcs,is,----

1. The process ol obtaining concentrated nitric acid from gas mixtures containing oxids of nitrogen, which includes the steps of absorbing the nitric oxid by means of a week basic oxid, and subsequently heating to a high temperature to drive out the nitric oxid in concentrated foriir 2. The process of obtaining' concentrated nitric acid from gas mixtures containing oxids of nitrogen, which consists'in absorbing the nitric OXNl by means of a week basic compound, subsequently heating; said basic compound to liberate the ul'isorbed nitric oxid, and absorbing said oxid in water to produce commercial acid.

3. The process of obtaining concentrated nitric acid from gas mixtures containing oxids of nitrogen, the steps which consist in ubsorbing the nitric ox'id from the gases by means of a weak basic oxid and then doc-omposing the compound thus formed at less than atmospheric pressure.

4. The pro 'css which consists in passing a mixture of nitric oxid and air over a weak basic oxid, thereby forming at decomposable material, and subsequent ly decon iposiug said material by heating at less than atmospheric pressure to liberate nitric oxid.

5. The process which consists in pass ng a mixture of nitric mud endeir over a week in this casc the some ru 'iidity of nitric oxid in conaentmted form, and absuruing said oxid in water to fOl'lfl nitric acid. In In witness whereof, I have hereunto set my hand (his 3rd day of July, 1907.

1.1. GLASER.

basin oxid, Lherehy forming a, decomposable tnlnlmuml, and subsequently decon'lpnsin said compound. to liberate said nitric uxi in mlu-entiralied form.

6. The rucess which consists in passing dilute nitric oxid over a basic oxid to form a decomposable (:mnpnumi, subsec'uently do composing said compound Lu iiimmte said Witnesses:

MAX HAMnuuumn, 03mm 81mm. 

